there are a lot of them you just have to listen and download what you like! b.o.b is a good artist that interchanges rap and singing in pretty much all his songs. Also if you have an artist in mind that you like, plug him in on Pandora and you'll find numerous more that are about the same!
These are some of the music songs with some rap on them like Tre Gottie sniper Ceaza by Amnesia, On my Grind Lucky fet Blacka. The rap music originated in the middle of the 1970's though the music did not get popularity as now.